Carburetor for multicylinder internal combustion engines



T. A. MORRIS 2,318,008

CARBURETOR FOR MULTICYLINDER INTERNAL COMBUSTION ENGINES May 4, 1943.

Filed Dec. 23, 1940 INVENTOR. THOMAS A.MORRIS mm/fiwww- ATTORNEYS Patented May 4, 1943 UNITED SFTATES PATENT ome CARBURETCR FOR MULTICYLINDEIt INTERNAL COMBUSTIQN ENGINES Thomas A. Morris,l)etroit, Mich, asslgnor to National Devices Corporation. Detroit, Mich.

Application December 23, 1940. Serial No. 371,420

0 Claims. (Cl. i231l9) The invention relates to carburetors morelparticlil i'ly designed for Inulticylinder internal com? bustion engines and has for its object the obtaining of a more uniform combustible mixture in eachfolthe cylinders and under varying conditions; Some or the "conditions which interfere with successful operation ot multicylinder enzines are: V

1. Uneven'distribution oi the combustible mixture to thediflerentcylinders; v

2. Inequality in the iuel to air ratio of the mixture arriving in the different cylinders:

3. Variations due to temperature difierences;

4. Variations due to'atmospheric conditions:

5. Variations due to the falling out of the liquid fuel from the duringits passage from the carburetor to the cylinder;

6. Variations due tosurgingofthe mixture in the'maniiold. 1 It is the object oi the-invention to overcome the difliculties due to the conditions above re-' ierred to. and to this end the invention consists in the construction as hereinafter Inthedrawing:

F ure 1 is a side elevation of a manifold and carburetor asapplied to a multicylinderinternal combustion'en'ginep a Figure 2 is a vertical central section through one of the branches of. themanifold showing the fuel injection and controlling means therefor:

Figure} is a central section on line 3-3 of Figure i-through the regulator for the liquid fuel Figure 4 is a crass As illustrated, A is a manifold having a common inlet portion; 3 a plurality of branch portions C, C leading'to the several'cylinders or pairs of cylinders and an enlargedsurge chamber- D between-the inlet portion 3 and the branches. The branchesC, C, C? preferably extend vertically downward to the inlet ports in .thecylinder'hlock (not shown) and each branch set forth.

terial. such as fneoprenefl which is notdetrimentally ailected by the liquid fuel is placed on the head to form the seal. The metering pin G has a shank portion J which extends diametri-- cally across the venturi and out througha port in the oppositewall thereof into an auxiliary casing K. L is a flexible diaphragm extending across this casin andcentrally secured to the shank of the metering. pin G by suitable means.

such as washers L and nuts U engaging a threaded portionof the shank on opposite sides. of the diaphragm, Springs M and M on opposite sides of the diaphragm areproperly tensloned to yieldably hold the same in a normal position. diaphragm L divides the casing K into two chambers K and K the chamber K being connected suction stroke of the piston in the engine cylin der. the partial vacuum formed on the' englne side of the constriction will becommunicated to Q I the'chamber K" so that the externalatmospheric pressure will move said diaphragm inward openingthe port F but variably restricting the same according tothe position assumed by themetering' pin G. This position will be determined by section on line-H, Figure 2. k r

the difierential pressure on the diaphragm so that the higherthe vacuum, the greater the restriction of the portF. .When the pressure within the venturi and the chamber'K' rises; this will causean outward movement of the diaphragm but by reason of the fact that air is trapped in the chamber K due to the. closing oflthe check valve N, this outward movement is retarded. Consequently, when. the pulsations in the manifold are very rapid as where the engine is runventurLl The discharge of fuel throughthejp'ort P is controlled; by a metering devicev which; as

shown-inlflgure 2, cornprises atapering pin G- longitudinally movable in theport- F to variably 5 restrict the same.- Thereis also aheadH at the small end of the pin which forms a closure for the port when the carburetor is, not' in action thereby preventing leakage of the liquid. fuel into i the Venturi conduit a gasket I ofsuitable 'ma- 6 nine: at high speed, the lag in the movement of the diaphragm will be sufficient to hold itin a substantially constant position determined by the average depression in the venturl."

Changes in barometric pressure of the atmosphere will tend to modify the action ofv the diaphragm. This I have avoided by the use of an evacuated metallic bellows member 0 which is anchored to a bracket member 0' secured to the casing K and has its opposite end connected to a stem 0 passing through an aperture in the casing and provided at its inner end with an abutment 0 for the spring M., This will compens'ate for changes in. atmospheric pressure by movement of the abutment O inward when the barometric pressure falls so as to increase tension on the spring M while, on the other hand, an increase in barometric pressure will move the abutment O outward and decrease the tension of the spring M.

Changes in temperature causing expansion and contraction of the parts will tend to alter the metering function. Also increase in heat .will expand the air and render the liquid fuel less viscous. To compensate for these changes, I employ a thermostat which alters the length of the shank J between the diaphragm. and the metering pin. As shown, the shank J is formed in two sections J and J which have a .threaded engagement J with each other. Surrounding the shank centrally of the constricted portion of the venturi is a helical thermostatic bar P, one end of which is attached to the section J and the other to the section J". Changes of temperature in this bar will coil or 'uncoil the same relatively rotating the sections J and J and through the screw threaded engagement J altering the length.

To obtain accurate metering of the fuel, the pressure under which it'ls forcedthrough the metering device must remain as nearly as pos- .ssbleconstant.' I, therefore, employ a regulator Q which is shown in Figure 3 as a metering device Q controlled by a flexible resilient diaphragm Q The metering device consists 'of a tapering pin extending into a port Q through the diaphragm and the arrangement is such that when the fluid pressure is increased on the inlet side of the regulator, the diaphragm will be defiected so that the port Q is further restricted thereby reducing the pressure on the opposite side of the diaphragm and on the fuel in the conduit leading to the fuel injection ports F. In like manner, a decrease in the pressure on the fuel entering the regulator will cause the resilient diaphragm to move so as to increase the port area and thereby increase the pressure on the liquidwhich is delivered to the ports F. The

, total effect is to maintain a substantially constant pressure on the liquid fuel in the conduits adjacent .to the ports F.

ency for liquid fuel particles to drop out. When the engine is not in operation, the restoration of atmospheric pressure on the inner side of the diaphragm L will move the metering pin G outward seating the head 'H and its gasket I so as to close the port F. However, when the engine is in operation, the outward movement of the diaphragm is retarded as previously described due to the closing of the check valve M and the trapping of air in the chamber K There is, however, a slow leak for air out of this chamber preferably through a small port 0 at one side of the stem 0 as shown in Figure 4.

- My improved carburetor is one which is adapted for operation under various conditions, such for instance, as with engines for aircraft which operate under varying atmospheric pressures according to altitude. It is customary to provide superchargers for such use and under certain conditions the air supplied to the carburetoris supercharged and under other conditions it is not. My improved construction will adapt itself to this by a proper fashioning of the metering pin G which will automatically adjust the amount of fuel discharged in proportion to the quantity of air;

What I claim as my invention is:

1. In a carburetor, the combination with a 7 said metering means responsive to variations in pressure within said Venturi conduit to progressively restrict said port by decrease in pressure in the venturi and to c0mp1etely 'close,the port I when the pressure within atmosphere.

2. In .a carburetor, the" the Venturi is equal to combination I with a Venturi'conduit having a fuel injection port in the constricted portion thereof, of "metering means for the fuel passing through said port completely closing the port in one'position. a flexible diaphragm operatively connected with saidmetering means responsive to variations in pressure within said Venturi conduit to progres- In the complete operation, the air entering the common conduit B is controlled by a single throttle valve R which may be adjustedv to variably restrict said conduit. From the common portion B of the conduit,- the air passes to the several branches 0, C, C'passing therethrough and through the Venturi portions E into the engine cylinders (not shown). As the suction in these cylinders is successive, there will be a corresponding successive flow of air through same substantially in a position the several branch conduits but the enlarged 1 surge chamber D will prevent the movement of air in one branch conduit from materially affecting the movement in another branch conduit. The air in-passing through the Venturi will be commingled with the fuel injected through the port F and, as above'described, the area of this port is variably restricted by the metering I creasethe restriction of said portproportiona-l I. to decrease in .air-pressurein said chamberand' to close the port when the; air pressure is equal movement of position.

sively restrict said port by decrease in pressure in the venturi and-to-completely 'c'losethe port when the pressure withinthe venturi is equal to atmosphere, and means for retarding rapid oscillations of said diaphragm to maintain the the average pressure. i 3. Ina carburetor; the combination witha casthe constricted portion of the ventu ing member engaging said chamber in said casing having air connection with said-Venturi conduit, a flexible diaphrgam i chamber" and centrally connected to said metering member, said die: 1

extending :across said phragm being responsive to variations in pressure in said chamber and Venturi to ;progre'ssively into atmosphere, and'1 meansfor-retarding the 4; In a carbu ing having a'Vent'u'rl conduit therethrough and a fuel injectionport in theconstricted portion of corresponding to g-provided"with aVenturi conduit extending .therethrough and a fuelinjection or emrmg ri, of,a meter port and adapted to completely close the same in one "positionpa' said diaphragmltowards its normal retorfthe combination of a cassaid venturi, said casing being also provided with a portion forming a chamber having air connection with said Venturi conduit, a flexible diaphragm extending across said chamber," a metering member for variably restricting said port engaging the same from the inner side thereof and provided with a head at its outer end for completely closing said port, a shank for said metering member extending across said Venturi conduit and through a port in the opposite wall thereof into said chamber and connecting with said diaphragm whereby variations in pressure pressure on the liquid fuel delivered to said port,-

duit to progressively restrict said port by decrease in air pressure in the conduit and to completely in said chamber corresponding to pressure variations in the Venturi conduit will progressively increase the restriction of said port in proportion to decrease in air pressure and will close said port at atmospheric pressure, and means forming a chamber on the opposite side of said diaphragm having a restricted vent port and a free entrance port for air from the external atmosphere whereby rapid oscillations of said diaphragm are checked and said metering means is substantially held in a position corresponding to the average decrease in pressure in said first mentioned chamber.

5. In a carburetor, the combination with an air conduit having a fuel injection port therein, of metering means for the fuel passing through said port, and means for operating said metering means conjointly controlled by the pressure within the conduit, the temperature of the parts and barometric pressure of the atmosphere.

6. In a carburetor, the combination with a casing having a Venturi conduit extending therethrough and a fuel injection port in the constricted portion of the venturi, said casing being also provided with a portion forming a chamber having air communication with the venturi, a diaphragm extending across said casing, a metering member for engaging said port to variably restrict the same, a shank for said metering member formed in two portions having a threaded engagement with each other, said shank extending across said venturi through a port in the opposite wall thereof into said chamber and being connected to said diaphragm, and a thermostatic member surrounding said shank within saidventuri and connected to the separate portions of said shank whereby temperature variations will relatively rotate said shank portions and correspondingly vary the combined length thereof. l

'7. In a. carburetor, the combination with an air conduit having a fuel injection port therein, of means for supplying liquid fuel to said port, means for maintaining a substantially constant close the port when the air pressure is equal to atmosphere, and means for retarding rapid oscillations of said diaphragm to maintain the same substantially in a position corresponding to the average pressure in the conduit.

8. In a carburetor for multicylinder internal combustion engines, an inlet conduit having a common portion and a plurality of branch portions extending therefrom with an enlarged surge chamber intermediate said common portion and said branch portions, each of said branch portions having a vertically downwardly extending suction portion, a single throttle for controlling said common conduit portion, individual liquid fuel injection means for each branch conduit having a discharge port therein, metering means for each discharge port, and means responsive to pressure in the branch conduit for operating said metering means to restrict the area of discharge in proportion to decrease in pressure in said conduit.

9. In a carburetor, the combination with an air conduit having a fuel injection port therein, of metering means forthe fuel passing through said port completely closing the port in one position, and a flexible diaphragm operatively connected with said metering means responsive to variations in pressure within said conduit to progressively restrict said port by decrease in pressure in the conduit and to completely close the port when the pressure .within the conduit is equal to atmosphere.

10. In a carburetor, the combination with anair conduit having a fuel injectionport in the constricted portion thereof, of metering means for the fuel passing through said port completely closing the port in one position, a flexible diaphragm operatively connected with said metering means responsive to variations in pressure within said conduit to'progressively restrict said port by decrease in pressure .in the conduit and to completely close the port when the pressure within the conduit is equal to atmosphere, and

means for retarding rapid oscillations of said diaphragm to maintain the same substantially in a position corresponding to the average pressure.

THOMAS A. MORRIS. 

